Spectroscopic measurements of plasma inside the keyhole in deep penetration laser welding
Spectroscopic measurements of plasma inside the keyhole in deep penetration laser welding
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DOI：
10.1088/0022-3727/38/5/007
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发表时间：
2005-03-07
影响因子：
3.4
通讯作者：
Zhang, G
中科院分区：
文献类型：
--
作者：
Zhang, Y;Li, LJ;Zhang, G
深熔激光焊接与高电荷密度的剧烈等离子体产生有关。等离子体驻留在小孔外部和内部，分别称为等离子体羽流和小孔等离子体。小孔外的等离子体羽流因其便于观察而被广泛研究，但对小孔等离子体的分析工作却很少。本文利用一套专门设计的装置，对铝薄膜激光深熔焊中夹在两片GG17玻璃之间的小孔等离子体光发射进行了第一手测量，成功地消除了小孔等离子体羽流对小孔等离子体观察的影响。采用正交试验设计，获得了焊接条件下等离子体羽流和小孔等离子体的光谱测量结果。结果表明，小孔等离子体对入射激光对材料的能量传递效率有很大影响，表现出不同的熔化宽度和深度；通过减小铝膜厚度来降低小孔等离子体的密度，可以获得更深的焊接深度和更低的小孔等离子体温度。
Deep penetration laser welding is associated with violent plasma generation characterized by high charge densities. The plasma resides both outside and inside the keyhole, and is called plasma plume and keyhole plasma, respectively. The plasma plume outside the keyhole has been studied extensively because it can be conveniently observed; however, very little work has concentrated on the analysis of the keyhole plasma. In this paper, a specially designed set-up was used to take firsthand measurements of the light emission of the keyhole plasma in deep penetration laser welding aluminium films, clamped in between two pieces of GG17 glass, which we called a 'sandwich' sample, thus triumphantly eliminating the effect of the plasma plume covering the keyhole on the observation of the keyhole plasma. Results of spectroscopic measurements of both the plasma plume and keyhole plasma under welding conditions were obtained with an orthogonal experimental design. It was shown that the keyhole plasma had a considerable effect on the energy transfer efficiency of the incident laser beam to the material, exhibiting various melting widths and depths; a deeper welding depth as well as a lower temperature of the keyhole plasma was obtained when the density of the keyhole plasma was decreased by reducing the thickness of the aluminium films.